Switching rocker arm assembly having eccentric axle for lash adjustment

ABSTRACT

A switching rocker arm assembly constructed in accordance to one example of the present teachings includes an outer arm, an inner arm, a bearing axle and a pivot axle. The outer arm can have a first outer side arm and a second outer side arm. The outer arm can define outer bores. The inner arm can have a first inner side arm and a second inner side arm. The inner arm can be disposed between the first and second outer side arms. The inner arm can define inner bores. The bearing axle can support a bearing. One of the bearing axle and pivot axle comprises (i) a central axle body having a central centerline, (ii) a first axle end body having a first centerline and (iii) a second axle end body having a second centerline. The central centerline is offset from at least one of the first and second centerlines.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No. PCT/US2016/029515 filed Apr. 27, 2016 which claims the benefit of U.S. patent application Ser. No. 62/153,004 filed on Apr. 27, 2015. The disclosure of the above application is incorporated herein by reference.

FIELD

The present disclosure relates generally to switching roller finger followers or rocker arms in internal combustion engines.

BACKGROUND

Variable valve actuation (WA) technologies have been introduced and documented. One WA device may be a variable valve lift (VVL) system, a cylinder deactivation (CDA) system such as that described in U.S. Pat. No. 8,215,275 entitled “Single Lobe Deactivating Rocker Arm” hereby incorporated by reference in its entirety, or other valve actuation systems. Such mechanisms are developed to improve performance, fuel economy, and/or reduce emissions of the engine. Several types of the WA rocker arm assemblies include an inner rocker arm within an outer rocker arm that are biased together with torsion springs.

Switching rocker arms allow for control of valve actuation by alternating between latched and unlatched states. A latch, when in a latched position causes both the inner and outer rocker arms to move as a single unit. When unlatched, the rocker arms are allowed to move independent of each other. In some circumstances, these arms can engage different cam lobes, such as low-lift lobes, high-lift lobes, and no-lift lobes. Mechanisms are required for switching rocker arm modes in a manner suited for operation of internal combustion engines.

The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

SUMMARY

A switching rocker arm assembly constructed in accordance to one example of the present teachings includes an outer arm, an inner arm, a bearing axle and a pivot axle. The outer arm can have a first outer side arm and a second outer side arm. The outer arm can define outer bores. The inner arm can have a first inner side arm and a second inner side arm. The inner arm can be disposed between the first and second outer side arms. The inner arm can define inner bores. The bearing axle can support a bearing. The pivot axle can cooperate with the outer and inner arms. One of the bearing axle and pivot axle comprises (i) a central axle body having a central centerline, (ii) a first axle end body having a first centerline and (iii) a second axle end body having a second centerline. The central centerline is offset from at least one of the first and second centerlines.

According to additional features, the central axle body locates between the first and second inner side arms. The central centerline can be offset relative to the first and second centerlines a distance equal to a desired mechanical lash adjustment desired in the switching rocker arm assembly. The first and second centerlines are coaxial. The pivot axle is eccentric. The switching rocker arm assembly can further comprise an elephant foot (e-foot). The e-foot is assembled between the central axle body of the pivot axle and the valve. Rotation of the pivot axle causes the e-foot to move relative to the valve. The pivot axle defines a tool engaging feature on one of the first and second axle end bodies. The pivot axle secures the inner arm to the outer arm while also allowing a rotational degree of freedom wherein one of the outer and inner arms rotates relative to the other of the outer and inner arms about the pivot axle when the switching rocker arm assembly is in a deactivated state. One of the inner and outer rocker arms defines a passage that extends to a corresponding bore that receives the pivot axle.

According to other features, the switching rocker arm can further comprise a securing member disposed through the passage that fixes the pivot axle relative to the one of the inner and outer rocker arms subsequent to setting lash. The securing member can comprise flowable plastic that is configured to solidify. The pivot axle can define an annular groove around one of the first and second axle end bodies. The securing member locates within the annular groove.

In one configuration the bearing axle is eccentric. The bearing is configured to engage a cam lobe. Rotation of the bearing axle causes the bearing to move relative to the cam lobe to adjust mechanical lash. The bearing axle is supported on opposite ends by torsion spring ends. One of the inner and outer rocker arms defines a passage. The switching rocker arm can further comprise a securing member disposed through the passage that fixes the bearing axle relative to the one of the inner and outer rocker arms subsequent to setting lash. The bearing axle defines an annular groove around one of the first and second axle end bodies. The securing member locates within the annular groove.

A rocker arm constructed in accordance to additional features includes an outer arm, a bearing axle and a pivot axle. The outer arm can have a first outer side arm and a second outer side arm, the outer arm defining outer bores. The bearing axle can extend through the first and second outer side arms and that supports a bearing. The pivot axle that pivotally supports the outer arm. One of the bearing axle and pivot axle comprises (i) a central axle body having a central centerline, (ii) a first axle end body having a first centerline and (iii) a second axle end body having a second centerline. The central centerline is offset from at least one of the first and second centerlines.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a front perspective view of an exemplary switching rocker arm incorporating a pivot axle constructed in accordance to one example of the present disclosure, the switching rocker arm shown with an exemplary valve and lash adjuster;

FIG. 2 is a perspective view of the switching rocker arm of FIG. 1 constructed in accordance to one example of prior art;

FIG. 3 is a first perspective view of the pivot axle of FIG. 2, the pivot axle having an eccentric profile;

FIG. 4 is a second perspective view of the pivot axle of FIG. 2;

FIG. 5 is a sectional view of the pivot axle, inner rocker arm and outer rocker arm according to one configuration of the present disclosure;

FIG. 6 is a side view of the switching rocker arm of FIG. 2;

FIG. 7 is a sectional view of the switching rocker arm of FIG. 6;

FIG. 8 is am exploded perspective view of an inner rocker arm and an outer rocker arm of a switching rocker arm constructed in accordance to another example of the present disclosure;

FIG. 9 is a perspective view of a roller bearing axle having an eccentric profile and constructed in accordance to another example of the present disclosure; and

FIG. 10 is a sectional view of the bearing axle, inner rocker arm and outer rocker arm of FIG. 8.

DETAILED DESCRIPTION

With initial reference to FIGS. 1-2, an exemplary switching rocker arm constructed in accordance to one example of prior art is shown and generally identified at reference 10. The switching rocker arm assembly 10 can be a compact cam-driven single-lobe cylinder deactivation (CDA-1L) switching rocker arm installed on a piston-driven internal combustion engine, and actuated with the combination of a duel-feed hydraulic lash adjusters (DFHLA) 12 that receive oil from oil control valves (“OCV”, not shown). The switching rocker arm assembly 10 can be engaged by a single lobe cam 20. The switching rocker arm assembly 10 can include an inner arm 22 and an outer arm 24. The default configuration is in the normal-lift (latched) position where the inner arm 22 and the outer arm 24 are locked together, causing an engine valve 26 to open and allowing the cylinder to operate as it would in a standard valvetrain. The DFHLA 12 has two oil ports. A lower oil port 28 provides lash compensation and is fed engine oil similar to a standard HLA. An upper oil port 30, referred as the switching pressure port, provides the conduit between controlled oil pressure from the OCV and a latch 32. When the latch 32 is engaged, the inner arm 22 and the outer arm 24 operate together like a standard rocker arm to open the engine valve 26. In the no-lift (unlatched) position, the inner arm 22 and the outer arm 24 can move independently to enable cylinder deactivation.

A pair of lost motion torsion springs 40 are incorporated to bias the position of the inner arm 22 so that it always maintains continuous contact with the camshaft lobe 20. The torsion springs 40 are secured to mounts located on the outer arm 24 by spring retainers 44. The spring retainers 44 retain the torsion springs 40 laterally. The lost motion torsion springs 40 require a higher preload than designs that use multiple lobes to facilitate continuous contact between the camshaft lobe 20 and an inner arm bearing 50 having a roller follower 52.

The outer arm 24 can have a first outer side arm 64 and a second outer side arm 66. The inner arm 22 can be disposed between the first outer side arm 64 and the second outer side arm 66. The inner arm 22 can have a first inner side arm 70 and a second inner side arm 72. The inner arm 22 and the outer arm 24 are both mounted to a pivot axle 74. The pivot axle 74 can be located adjacent to a first end of the rocker arm assembly 10, which secures the inner arm 22 to the outer arm 24 while also allowing a rotational degree of freedom pivoting about the pivot axle 74 when the rocker arm assembly 10 is in a deactivated state. As will be described herein, the pivot axle 74 has an eccentric geometry that allows the pivot axle 74 to rotate about its central axis within the inner and outer arms 22, 24 adjusting lash of the rocker arm assembly 10 between the valve 26 and the roller follower 52.

The bearing 50 and roller follower 52 are mounted between the first inner side arm 70 and the second inner side arm 72 on a bearing axle 80 that, during normal operation of the rocker arm assembly 10 serves to transfer energy from the rotating cam 20 to the rocker arm assembly 10. The bearing axle 80 is biased upwardly by bearing axle springs 40.

With further reference now to FIGS. 3-7, additional features of the present disclosure will be described. Mechanical lash can be set mechanically with a valve tip cap 100. It will be appreciated that a plurality of valve tip caps 100 may be provided having different geometries. A suitable valve tip cap 100 can be assembled between an elephant foot (e-foot) 102 and the engine valve 26 (FIG. 1) to take up the variance on the rocker arm assembly 10 between the engine valve 26, the cam 20 and the DFHLA 12. In one configuration, the use of such valve tip caps 100 may be eliminated with the use of the pivot axle 74. Although, in some configurations the pivot axle 74 may be used in concert with a valve tip cap 100.

The pivot axle 74 includes a central axle body 110, a first axle end body 112 and a second axle end body 114. The central axle body 110 can be undercut and have a central outer surface 116. The first axle end body 112 and the second axle end body 114 have corresponding first and second centerlines 122 and 124. The first and second centerlines 122 and 124 can be coaxial. The central axle body 110 has a central centerline 130. The central centerline 130 is not coaxial with the first and second centerlines 122 and 124. In this regard, as the pivot axle 74 is rotated around the first and second centerlines 122 and 124, the central axle body 110 will also rotate but while altering the position of the central outer surface 116. In other words, because the central centerline 130 is offset from the first and second centerlines 122 and 124, the central outer surface 116 of the central axle body 110 will move positions relative to the first axle end body 112 and the second axle end body 114. It will be appreciated that other shapes of the central axle body 110 are contemplated that allow the central outer surface 116 to move radially upon rotation of the pivot axle 74 around the centerlines 122 and 124.

During rotation of the pivot axle 74, as the central outer surface 116 moves locations, the e-foot 102 will also move. As the e-foot 102 moves toward and away from the valve 26, lash can be set. It will be appreciated that during the rotation, the first and second axle end bodies 112 and 114 ride within inner arm bores 132 in the inner rocker arm 122 and outer arm bores 134 in the outer rocker arm 24. During rotation of the pivot axle 74, the locations of the first and second rocker arms 22 and 24 are unchanged. The first axle end body 112 includes a tool engaging groove 140. A tool can engage the tool engaging groove 140 for imparting rotational motion on the pivot axle 74 during the lash adjustment. While not shown, a similar tool engaging groove may be incorporated on the second axle end body 114. The second axle end body 114 can define an annular groove 142. Once a desired lash has been set, the pivot axle 74 can be locked from further rotation.

With particular reference now to FIGS. 2 and 5, additional features of the present disclosure will be described. The outer rocker arm 24 can define a passage 160 that extends from an outer surface 162 of the outer rocker arm 24 to the outer arm bore 134. Once the desired lash has been set, a securing member in the form of flowable plastic 170 can be injected through the passage 160. The plastic 170 can solidify in the bore 134 and around the groove 142 to fix the pivot axle 74 relative to the outer rocker arm 24 and preclude axial movement of the pivot axle 74. Explained further, the plastic 170 precludes translation of the pivot axle 74 along the axes 122, 124. Moreover, the plastic 170 precludes rotational movement of the pivot axle 74 around the axes 122, 124 precluding radial movement of the pivot axle 74. The desired lash therefore is now fixed. It will be appreciated that other configurations may be employed for fixing the pivot axle 74 relative to the outer rocker arm 24 once the desired lash is set.

With reference now to FIGS. 8-10, a switching rocker arm constructed in accordance to additional features is shown and generally identified at reference numeral 210. The switching rocker arm 210 can be configured for use in a CDA-1L such as described above with respect to FIG. 1. The switching rocker arm assembly 210 can include an inner arm 222 and an outer arm 224. The default configuration is in the normal-lift (latched) position where the inner arm 222 and the outer arm 224 are locked together, causing an engine valve (see 26, FIG. 1) to open and allowing the cylinder to operate as it would in a standard valvetrain. When a latch 232 is engaged, the inner arm 222 and the outer arm 224 operate together like a standard rocker arm to open the engine valve. In the no-lift (unlatched) position, the inner arm 222 and the outer arm 224 can move independently to enable cylinder deactivation. A pair of lost motion torsion springs 240 are incorporated to bias the position of the inner arm 222 so that it always maintains continuous contact with a camshaft lobe (see 20, FIG. 1). The torsion springs 240 are secured to mounts located on the outer arm 224 by spring retainers 244. The spring retainers 244 retain the torsion springs 240 laterally. The lost motion torsion springs 240 require a higher preload than designs that use multiple lobes to facilitate continuous contact between the camshaft lobe 220 and an inner arm bearing 250 having a roller follower 252.

The outer arm 224 can have a first outer side arm 264 and a second outer side arm 266. The inner arm 222 can be disposed between the first outer side arm 264 and the second outer side arm 266. The inner arm 222 can have a first inner side arm 270 and a second inner side arm 272. The inner arm 222 and the outer arm 224 are both mounted to a pivot axle 274. The pivot axle 274 can be located adjacent to a first end of the rocker arm assembly 210, which secures the inner arm 222 to the outer arm 224 while also allowing a rotational degree of freedom pivoting about the pivot axle 274 when the rocker arm assembly 210 is in a deactivated state.

The bearing 250 and roller follower 252 are mounted between the first inner side arm 270 and the second inner side arm 272 on a bearing axle 280 that, during normal operation of the rocker arm assembly 210 serves to transfer energy from the rotating cam 220 to the rocker arm assembly 210. The bearing axle 280 is biased upwardly by bearing axle springs 240. The bearing axle 280 of the rocker arm assembly 210 has an eccentric geometry that allows the bearing axle 280 to rotate about its central axis within the inner and outer arms 222, 224 adjusting lash of the rocker arm assembly 210.

The bearing axle 280 includes a central axle body 310, a first axle end body 312 and a second axle end body 314. The central axle body 310 can be undercut and have a central outer surface 316. The first axle end body 312 and the second axle end body 314 have corresponding first and second centerlines 322 and 324. The first and second centerlines 322 and 324 can be coaxial. The central axle body 310 has a central centerline 330. The central centerline 330 is not coaxial with the first and second centerlines 322 and 324. In this regard, as the bearing axle 280 is rotated around the first and second centerlines 322 and 324, the central axle body 310 will also rotate but while altering the position of the central outer surface 316, therefore altering the position of the bearing 250 and a resulting location of contact between the bearing 250 with the cam (see 20, FIG. 1). This movement allows the system mechanical lash to be adjusted and set. In other words, because the central centerline 330 is offset from the first and second centerlines 322 and 324, the central outer surface 316 of the central axle body 310 will move positions relative to the first axle end body 312 and the second axle end body 314. It will be appreciated that other shapes of the central axle body 310 are contemplated that allow the central outer surface 316 to move radially upon rotation of the bearing axle 280 around the centerlines 322 and 324.

During rotation of the bearing axle 280, the first and second axle bodies 312 and 314 ride around a surface of the bearing axle springs 240. During rotation of the bearing axle 280, the locations of the first and second rocker arms 222 and 224 are unchanged, while the relative location of the bearing 250 changes. The second axle end body 314 includes a tool engaging groove 340. A tool can engage the tool engaging groove 340 for imparting rotational motion on the bearing axle 280 during the lash adjustment. While not shown, a similar tool engaging groove may be incorporated on the second axle end body 314. The second axle end body 314 can define an annular groove 342. Once a desired lash has been set, the bearing axle 280 can be locked from further rotation.

The inner rocker arm 222 can define a passage 360 that extends from an outer surface 362 of the inner rocker arm 222 to a bearing axle bore 364. Once the desired lash has been set, a securing member in the form of flowable plastic 370 can be injected through the passage 360. The plastic 370 can solidify in the bore 364 and around the groove 342 to fix the bearing axle 280 relative to the inner rocker arm 222 and preclude axial movement of the bearing axle 280. Explained further, the plastic 370 precludes translation of the bearing axle 280 along the axes 322, 324. Moreover, the plastic 370 precludes rotational movement of the bearing axle 280 around the axes 322, 324 precluding radial movement of the bearing axle 280. The desired lash therefore is now fixed. It will be appreciated that other configurations may be employed for fixing the bearing axle 280 relative to the inner rocker arm 222 once the desired lash is set. While the above bearing axle 280 has been described as part of a switching rocker arm 210, the same principals may be used in standard rocker arms.

The foregoing description of the examples has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular example are generally not limited to that particular example, but, where applicable, are interchangeable and can be used in a selected example, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. 

What is claimed is:
 1. A switching rocker arm assembly comprising: an outer arm having a first outer side arm and a second outer side arm, the outer arm defining outer bores; an inner arm having a first inner side arm and a second inner side arm, the inner arm disposed between the first and second outer side arms, the inner arm defining inner bores; a bearing axle that supports a bearing; and a pivot axle cooperating with the outer and inner arms; wherein one of the bearing axle and pivot axle comprises (i) a central axle body having a central centerline, (ii) a first axle end body having a first centerline and (iii) a second axle end body having a second centerline, wherein the central centerline is offset from at least one of the first and second centerlines.
 2. The switching rocker arm assembly of claim 1 wherein the central axle body locates between the first and second inner side arms.
 3. The switching rocker arm assembly of claim 2 wherein the central centerline is offset relative to the first and second centerlines a distance equal to a desired mechanical lash adjustment desired in the switching rocker arm assembly.
 4. The switching rocker arm assembly of claim 1 wherein the first and second centerlines are coaxial.
 5. The switching rocker arm assembly of claim 4 wherein the pivot axle is eccentric.
 6. The switching rocker arm assembly of claim 5, further comprising an elephant foot (e-foot), wherein the e-foot is assembled between the central axle body of the pivot axle and a valve, wherein rotation of the pivot axle causes the e-foot to move relative to the valve.
 7. The switching rocker arm assembly of claim 5 wherein the pivot axle defines a tool engaging feature on one of the first and second axle end bodies.
 8. The switching rocker arm assembly of claim 1 wherein the pivot axle secures the inner arm to the outer arm while also allowing a rotational degree of freedom wherein one of the outer and inner arms rotates relative to the other of the outer and inner arms about the pivot axle when the switching rocker arm assembly is in a deactivated state.
 9. The switching rocker arm assembly of claim 5 wherein one of the inner and outer rocker arms defines a passage that extends to a corresponding bore that receives the pivot axle.
 10. The switching rocker arm assembly of claim 9, further comprising a securing member disposed through the passage that fixes the pivot axle relative to the one of the inner and outer rocker arms subsequent to setting lash.
 11. The switching rocker arm assembly of claim 10 wherein the securing member comprises flowable plastic that is configured to solidify.
 12. The switching rocker arm assembly of claim 9 wherein the pivot axle defines an annular groove around one of the first and second axle end bodies, wherein the securing member locates within the annular groove.
 13. The switching rocker arm assembly of claim 1 wherein the bearing axle is eccentric.
 14. The switching rocker arm assembly of claim 13 wherein the bearing is configured to engage a cam lobe and wherein rotation of the bearing axle causes the bearing to move relative to the cam lobe to adjust mechanical lash.
 15. The switching rocker arm assembly of claim 14 wherein the bearing axle is supported on opposite ends by torsion spring ends.
 16. The switching rocker arm assembly of claim 14 wherein one of the inner and outer rocker arms defines a passage, the switching rocker arm further comprising: a securing member disposed through the passage that fixes the bearing axle relative to the one of the inner and outer rocker arms subsequent to setting lash.
 17. The switching rocker arm assembly of claim 16 wherein the securing member comprises flowable plastic that is configured to solidify.
 18. The switching rocker arm assembly of claim 17 wherein the bearing axle defines an annular groove around one of the first and second axle end bodies, wherein the securing member locates within the annular groove.
 19. A switching rocker arm assembly comprising: an outer arm having a first outer side arm and a second outer side arm, the outer arm defining outer bores; an inner arm having a first inner side arm and a second inner side arm, the inner arm disposed between the first and second outer side arms, the inner arm defining inner bores; a bearing axle that supports a bearing; a pivot axle cooperating with the outer and inner arms; and an elephant foot (e-foot); wherein the pivot axle comprises (i) a central axle body having a central centerline, (ii) a first axle end body having a first centerline and (iii) a second axle end body having a second centerline, wherein the central centerline is offset from at least one of the first and second centerlines, wherein the e-foot is assembled between the central axle body of the pivot axle and a valve, wherein rotation of the pivot axle causes the e-foot to move relative to the valve setting lash of the switching rocker arm assembly.
 20. The switching rocker arm assembly of claim 19 wherein the central axle body locates between the first and second inner side arms.
 21. The switching rocker arm assembly of claim 20 wherein the central centerline is offset relative to the first and second centerlines a distance equal to a desired mechanical lash adjustment desired in the switching rocker arm assembly.
 22. The switching rocker arm assembly of claim 19 wherein the first and second centerlines are coaxial.
 23. The switching rocker arm assembly of claim 22 wherein the pivot axle is eccentric.
 24. The switching rocker arm assembly of claim 19 wherein one of the inner and outer rocker arms defines a passage that extends to a corresponding bore that receives the pivot axle.
 25. The switching rocker arm assembly of claim 24, further comprising a securing member disposed through the passage that fixes the pivot axle relative to the one of the inner and outer rocker arms subsequent to setting lash.
 26. The switching rocker arm assembly of claim 25 wherein the securing member comprises flowable plastic that is configured to solidify.
 27. The switching rocker arm assembly of claim 26 wherein the pivot axle defines an annular groove around one of the first and second axle end bodies, wherein the securing member locates within the annular groove.
 28. A switching rocker arm assembly comprising: an outer arm having a first outer side arm and a second outer side arm, the outer arm defining outer bores; an inner arm having a first inner side arm and a second inner side arm, the inner arm disposed between the first and second outer side arms, the inner arm defining inner bores; a bearing axle that supports a bearing; and a pivot axle cooperating with the outer and inner arms; wherein the bearing axle comprises (i) a central axle body having a central centerline, (ii) a first axle end body having a first centerline and (iii) a second axle end body having a second centerline, wherein the central centerline is offset from at least one of the first and second centerlines, wherein the bearing is configured to engage a cam lobe and wherein rotation of the bearing axle causes the bearing to move relative to the cam lobe to adjust mechanical lash.
 29. The switching rocker arm assembly of claim 28 wherein the bearing axle is supported on opposite ends by torsion spring ends.
 30. The switching rocker arm assembly of claim 28 wherein one of the inner and outer rocker arms defines a passage, the switching rocker arm further comprising: a securing member disposed through the passage that fixes the bearing axle relative to the one of the inner and outer rocker arms subsequent to setting lash.
 31. The switching rocker arm assembly of claim 30 wherein the securing member comprises flowable plastic that is configured to solidify.
 32. The switching rocker arm assembly of claim 31 wherein the bearing axle defines an annular groove around one of the first and second axle end bodies, wherein the securing member locates within the annular groove. 